Currently used systems and methods for testing water—and airtight sealing of vehicles or vehicle parts—in particular, water—and airtight sealing of doors, windows or other vehicle parts involving sealing, seals, or other types of connections—comprise subjecting the test vehicle to simulated rain and/or storms. That is, at the end of the manufacturing stage, the vehicle is subjected to prolonged, powerful water jets, after which an operator visually inspects the inside of the vehicle for water. If the test proves positive, this means the watertightness of the part of the vehicle letting in water needs improving. Locating the fault, however, may prove difficult or even impossible, on account of the poor accuracy of the known method described. Very often, in fact, failure to accurately locate the fault makes it preferable to change the whole seal or reseal.